Neurons, Hormones, and Nervous System Function
Synapses and Neurotransmitters
Synapses are connections between neurons that transmit nerve impulses. A neurotransmitter is a chemical substance that produces the nerve impulse across the synapse.
Neuron Structure
Neurons possess filamentous extensions that facilitate connections with other neurons and organs throughout our body. We distinguish two main parts:
- Soma: Contains the nucleus and the main part of the cytoplasm.
- Extensions: There are two types:
- Dendrites: Short and highly branched extensions
Predator-Prey Dynamics, Symbiosis, and Ecosystem Interactions
Predator and Prey Relationships
Predators possess traits or skills that help them catch and kill their prey. Different types of predators have different skills and traits. For example, a cheetah uses its speed to catch prey. On the other hand, tigers have colors that let them blend with the environment so that prey cannot see them easily.
Prey generally have some way to protect themselves from being eaten. Different types of organisms protect themselves in different ways:
- Run Away: When a rabbit is
Human Anatomy: Digestive, Connective Tissues, and More
The Human Body: Anatomy and Physiology
Digestive System
The digestive system consists of the gastrointestinal tract (alimentary canal) and accessory digestive organs. The stages of digestion include:
- Ingestion: Food enters the mouth.
- Mastication: Chewing and mixing with saliva.
- Deglutition: Food moves to the pharynx and esophagus.
- Peristalsis: Wave-like contractions move food.
- Digestion: Mechanical and chemical breakdown.
- Absorption: Nutrients pass through the GI tract.
- Defecation: Waste elimination.
The
Read MoreUnderstanding Genetic Mutations: Types, Causes, and Repair Mechanisms
Mutations: An Overview
Mutations: Genetic material randomly modifies, which is of great importance in evolution.
Somatic cell mutations do not pass to descendants.
Germline cell mutations can be passed on and fixed in offspring.
- Negative mutations can be lethal.
- Beneficial mutations drive evolution.
Mutagenic agents can be physical, chemical, or biological.
Types of Mutations
- Gene mutations: Affect the gene.
- Chromosomal mutations: Affect chromosomal structure.
- Genomic mutations: Affect the number of chromosomal
Cardiovascular System: Physiology, Adaptations, and Function
Altitude Adaptations and Blood
- Altitude and Oxygen: With increasing altitude, atmospheric pressure decreases, resulting in less oxygen availability. This leads to lower oxygen pressure in the blood (hypoxemia), causing difficulty in breathing. Adaptive mechanisms to compensate for this include:
- Hyperventilation
- Polycythemia
- Blood Analysis at High Altitudes: Individuals who have lived at high altitudes for years exhibit increased hematocrit and higher amounts of hemoglobin in their blood.
- Red Blood Cells:
Renal Function, Digestion, and Thyroid Hormone Actions
Mechanisms of Dilute Urine Formation
Occurs in situations of overhydration.
Proximal Tubule
Water reabsorption is proportional to solute reabsorption. The tubular fluid remains isosmotic to plasma (osmolarity is constant).
Descending Loop of Henle
The renal medulla is hyperosmolar, increasing in concentration deeper towards the renal papillae. Water moves out into the hyperosmolar interstitium. Solutes are not reabsorbed. Intratubular osmolarity increases.
Ascending Loop of Henle
This segment is impermeable